DICHLOROMETHYLENATION OF LACTONES .6. EFFICIENT SYNTHESIS OF DICHLOROOLEFINS FROM LACTONES AND ACETATES USING TRIPHENYLPHOSPHINE AND TETRACHLOROMETHANE

Triphenylphosphine and tetrachloromethane react cleanly in refluxing t etrahydrofuran with substituted gamma and delta-lactones and some este rs to afford the corresponding dichloroolefins in good yields. This ne w Wittig-type reaction provides an easy entry to this new class of com pounds and tolerates a large variety of protecting groups. Application of this methodology to the dichloroolefination of simple lactones, su gar-derived lactones, and other biologically significant lactones is d escribed.